At one gym a few years (16) ago the PT did a whole body fat measurement as far as I can recall. It simply involved lying on the couch and having a couple of electrodes put on you.
I seem to remember it measured fat and muscle and as such was a more sensible measure. It had nothing to do with height, weight, age, or pinch an inch.
Some people are so hard fat that you couldn't pinch an inch if you tried.